With the development of communications technology and multimedia encoding/decoding technology, more and more portable terminal apparatus, such as mobile phone, netbook, electronic book and Personal Digital Assistant (PDA), are provided with media play functions.
In order to support media play function, a decoder is provided to portable terminal apparatus, which is used to decode a compressed bit stream into video frames. FIG. 1 is a structure schematic diagram of a decoder according to the prior art, which includes an entropy decoding module, a residual processing module, an intra-frame predicting module, an inter-frame predicting module and a deblocking filtering module. Specifically, the entropy decoding module performs entropy decoding on the compressed bit stream to obtain information such as a residual, a block type, a prediction mode, a motion vector and a reference frame number. The residual processing module performs an inverse scanning, an inverse quantization and an inverse transformation on the residual obtained by the entropy decoding. The intra-frame predicting module and the inter-frame predicting module extract corresponding reference image data from a reference frame to generate a predicting block, according to information such as the block type, the prediction mode, the motion vector and the reference frame number obtained by the entropy decoding. The predicting block is superposed with a residual block generated by the residual processing module, and then the deblocking filtering is performed by the deblocking filtering module, to obtain the output video frame.
The inventor of the present invention finds that there are at least the following problems in the prior art.
The decoder of the portable terminal apparatus is mainly powered by a battery, which limits the standby time and operation time of the decoder. Thus, the decoder can not support long-time multimedia play, and multimedia file will not be completely played due to low electrical quantity.